1. Field of the Invention
This invention relates to a display apparatus which includes a display and a backlight and a driving method for the display apparatus.
2. Description of the Related Art
In a liquid crystal display apparatus, liquid crystal material itself does not emit light. Accordingly, a backlight of the direct type is disposed on the back side of the liquid crystal display apparatus. In a color liquid crystal display apparatus, one pixel is formed typically from three sub-pixels including a red light emitting sub-pixel, a green light emitting sub-pixel and a blue light emitting sub-pixel. A liquid crystal cell which forms each pixel or each sub-pixel operates as an optical shutter (light valve) to control the light transmission factor or numerical aperture of the pixel or sub-pixel thereby to control the light transmission factor of illumination light typically in the form of which light emitted from the backlight to display an image.
In the related art, a backlight illuminated an entire liquid crystal display apparatus uniformly and with a fixed brightness. However, another backlight having a different configuration has been proposed and is disclosed, for example, in Japanese Patent Laid-Open No. 2004-258403. The backlight mentioned includes a plurality of light source units corresponding to a plurality of display area units which form a display area of a liquid crystal display apparatus and includes a mechanism for varying the distribution of the illuminance of the display area units.
By such control of the backlight (also called divisional driving of the backlight), increase of the contrast ratio by increase of the white level and decrease of the black level of a liquid crystal display apparatus can be anticipated. As a result, enhancement of the quality of image display can be anticipated, and reduction of the power consumption of the backlight can be anticipated.